diff options
| author | Nicolas Iooss <nicolas.iooss_linux@m4x.org> | 2015-07-17 16:23:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-07-17 16:39:53 -0700 |
| commit | 3958b79266b14729edd61daf9dfb84de45f4ec6d (patch) | |
| tree | 05990191af23a2632884358d40e173dfcb134219 | |
| parent | 8db1486065141e619e4855b84e350ef32064f7e1 (diff) | |
configfs: fix kernel infoleak through user-controlled format string
Some modules call config_item_init_type_name() and config_group_init_type_name()
with parameter "name" directly controlled by userspace. These two
functions call config_item_set_name() with this name used as a format
string, which can be used to leak information such as content of the
stack to userspace.
For example, make_netconsole_target() in netconsole module calls
config_item_init_type_name() with the name of a newly-created directory.
This means that the following commands give some unexpected output, with
configfs mounted in /sys/kernel/config/ and on a system with a
configured eth0 ethernet interface:
# modprobe netconsole
# mkdir /sys/kernel/config/netconsole/target_%lx
# echo eth0 > /sys/kernel/config/netconsole/target_%lx/dev_name
# echo 1 > /sys/kernel/config/netconsole/target_%lx/enabled
# echo eth0 > /sys/kernel/config/netconsole/target_%lx/dev_name
# dmesg |tail -n1
[ 142.697668] netconsole: target (target_ffffffffc0ae8080) is
enabled, disable to update parameters
The directory name is correct but %lx has been interpreted in the
internal item name, displayed here in the error message used by
store_dev_name() in drivers/net/netconsole.c.
To fix this, update every caller of config_item_set_name to use "%s"
when operating on untrusted input.
This issue was found using -Wformat-security gcc flag, once a __printf
attribute has been added to config_item_set_name().
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Felipe Balbi <balbi@ti.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | drivers/usb/gadget/configfs.c | 2 | ||||
| -rw-r--r-- | fs/configfs/item.c | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c index 0495c94a23d7..289e20119fea 100644 --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -571,7 +571,7 @@ static struct config_group *function_make( if (IS_ERR(fi)) return ERR_CAST(fi); - ret = config_item_set_name(&fi->group.cg_item, name); + ret = config_item_set_name(&fi->group.cg_item, "%s", name); if (ret) { usb_put_function_instance(fi); return ERR_PTR(ret); diff --git a/fs/configfs/item.c b/fs/configfs/item.c index 4d6a30e76168..b863a09cd2f1 100644 --- a/fs/configfs/item.c +++ b/fs/configfs/item.c @@ -115,7 +115,7 @@ void config_item_init_type_name(struct config_item *item, const char *name, struct config_item_type *type) { - config_item_set_name(item, name); + config_item_set_name(item, "%s", name); item->ci_type = type; config_item_init(item); } @@ -124,7 +124,7 @@ EXPORT_SYMBOL(config_item_init_type_name); void config_group_init_type_name(struct config_group *group, const char *name, struct config_item_type *type) { - config_item_set_name(&group->cg_item, name); + config_item_set_name(&group->cg_item, "%s", name); group->cg_item.ci_type = type; config_group_init(group); } |